U.S. Pat. No. 3,329,113 discloses a device with a cutting device and with sensors, whose distance from the cutting device is variable. The cutting device is activated by a signal of the sensor that is the front sensor in the direction of feed for a first cutting process. The first cutting process cuts through a connection means for a plurality of fabric parts, at a distance from the front edge of the respective fabric. This distance depends on the distance between this sensor and the cutting device. The cutting device is activated by a signal of the rear sensor for another cutting process, by which the connection means is cut through at a distance from the rear edge of the fabric, which distance depends on the distance between this sensor and the cutting device.
On a fabric that has hem projection lengths relative to its front and rear edges, the hem projection lengths can be shortened to a predeterminable length by this device. If the hem projection lengths are to be folded over at the respective fabric edge and they are to be pushed into the associated part of the hem, at least this part of the hem must not have a seam connection with the rest of the fabric part. However, the above mentioned U.S. Pat. No. 3,329,113 does not indicate how the seam formation could be limited to the middle part of the hem.
A device with a stitch counter is described in U.S. Pat. No. 4,276,837; this stitch counter is switched on as soon as the distance between the rear edge of the fabric and the stitch formation site, which distance is indicated by a sensor, drops below a predetermined value, and it remains in operation until it reaches a predeterminable end value. A feed distance for the fabric, which is obtained from the predetermined distance from the stitch formation site minus the width of a seamless rear fabric edge, is associated with this end value. Seam formation is terminated when the end value is reached.
Although the width of the seamless rear fabric edge can be preselected by this device by presetting the end value, it is necessary to reset the stitch counter if the fabric has hem projection lengths, and the width of the seamless rear fabric edge is to be adjusted to the rear hem projection length each time the length of this hem projection length changes. Since the above mentioned U.S. Pat. No. 4,276,837 contains no data on this, it can be assumed that the resetting must be performed by the operator.
Contrary to the seamless rear fabric edge, the formation of a similar front fabric edge is not possible with this device.